/*
 * utils.c - various utility functions used in pppd.
 *
 * Copyright (c) 1999-2002 Paul Mackerras. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. The name(s) of the authors of this software must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission.
 *
 * 3. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by Paul Mackerras
 *     <paulus@samba.org>".
 *
 * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "netif/ppp/ppp_opts.h"
#if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */

#if 0 /* UNUSED */
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <netinet/in.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/param.h>
#include <sys/resource.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <syslog.h>
#include <time.h>
#include <unistd.h>
#include <utmp.h>
#ifdef SVR4
#include <sys/mkdev.h>
#endif
#endif /* UNUSED */

#include "netif/ppp/ppp_impl.h"

#include "netif/ppp/fsm.h"
#include "netif/ppp/lcp.h"

#if defined(SUNOS4)
extern char *strerror();
#endif

static void ppp_logit(int level, const char *fmt, va_list args);
static void ppp_log_write(int level, char *buf);
#if PRINTPKT_SUPPORT
static void ppp_vslp_printer(void *arg, const char *fmt, ...);
static void ppp_format_packet(const u_char *p, int len,
                              void (*printer)(void *, const char *, ...),
                              void *arg);

struct buffer_info {
  char *ptr;
  int len;
};
#endif /* PRINTPKT_SUPPORT */

/*
 * ppp_strlcpy - like strcpy/strncpy, doesn't overflow destination buffer,
 * always leaves destination null-terminated (for len > 0).
 */
size_t ppp_strlcpy(char *dest, const char *src, size_t len) {
  size_t ret = strlen(src);

  if (len != 0) {
    if (ret < len)
      strcpy(dest, src);
    else {
      strncpy(dest, src, len - 1);
      dest[len - 1] = 0;
    }
  }
  return ret;
}

/*
 * ppp_strlcat - like strcat/strncat, doesn't overflow destination buffer,
 * always leaves destination null-terminated (for len > 0).
 */
size_t ppp_strlcat(char *dest, const char *src, size_t len) {
  size_t dlen = strlen(dest);

  return dlen + ppp_strlcpy(dest + dlen, src, (len > dlen ? len - dlen : 0));
}

/*
 * ppp_slprintf - format a message into a buffer.  Like sprintf except we
 * also specify the length of the output buffer, and we handle
 * %m (error message), %v (visible string),
 * %q (quoted string), %t (current time) and %I (IP address) formats.
 * Doesn't do floating-point formats.
 * Returns the number of chars put into buf.
 */
int ppp_slprintf(char *buf, int buflen, const char *fmt, ...) {
  va_list args;
  int n;

  va_start(args, fmt);
  n = ppp_vslprintf(buf, buflen, fmt, args);
  va_end(args);
  return n;
}

/*
 * ppp_vslprintf - like ppp_slprintf, takes a va_list instead of a list of args.
 */
#define OUTCHAR(c) (buflen > 0 ? (--buflen, *buf++ = (c)) : 0)

int ppp_vslprintf(char *buf, int buflen, const char *fmt, va_list args) {
  int c, i, n;
  int width, prec, fillch;
  int base, len, neg, quoted;
  unsigned long val = 0;
  const char *f;
  char *str, *buf0;
  const unsigned char *p;
  char num[32];
#if 0  /* need port */
    time_t t;
#endif /* need port */
  u32_t ip;
  static char hexchars[] = "0123456789abcdef";
#if PRINTPKT_SUPPORT
  struct buffer_info bufinfo;
#endif /* PRINTPKT_SUPPORT */

  buf0 = buf;
  --buflen;
  while (buflen > 0) {
    for (f = fmt; *f != '%' && *f != 0; ++f)
      ;
    if (f > fmt) {
      len = f - fmt;
      if (len > buflen)
        len = buflen;
      memcpy(buf, fmt, len);
      buf += len;
      buflen -= len;
      fmt = f;
    }
    if (*fmt == 0)
      break;
    c = *++fmt;
    width = 0;
    prec = -1;
    fillch = ' ';
    if (c == '0') {
      fillch = '0';
      c = *++fmt;
    }
    if (c == '*') {
      width = va_arg(args, int);
      c = *++fmt;
    } else {
      while (lwip_isdigit(c)) {
        width = width * 10 + c - '0';
        c = *++fmt;
      }
    }
    if (c == '.') {
      c = *++fmt;
      if (c == '*') {
        prec = va_arg(args, int);
        c = *++fmt;
      } else {
        prec = 0;
        while (lwip_isdigit(c)) {
          prec = prec * 10 + c - '0';
          c = *++fmt;
        }
      }
    }
    str = 0;
    base = 0;
    neg = 0;
    ++fmt;
    switch (c) {
    case 'l':
      c = *fmt++;
      switch (c) {
      case 'd':
        val = va_arg(args, long);
        if ((long)val < 0) {
          neg = 1;
          val = (unsigned long)-(long)val;
        }
        base = 10;
        break;
      case 'u':
        val = va_arg(args, unsigned long);
        base = 10;
        break;
      default:
        OUTCHAR('%');
        OUTCHAR('l');
        --fmt; /* so %lz outputs %lz etc. */
        continue;
      }
      break;
    case 'd':
      i = va_arg(args, int);
      if (i < 0) {
        neg = 1;
        val = -i;
      } else
        val = i;
      base = 10;
      break;
    case 'u':
      val = va_arg(args, unsigned int);
      base = 10;
      break;
    case 'o':
      val = va_arg(args, unsigned int);
      base = 8;
      break;
    case 'x':
    case 'X':
      val = va_arg(args, unsigned int);
      base = 16;
      break;
#if 0  /* unused (and wrong on LLP64 systems) */
	case 'p':
	    val = (unsigned long) va_arg(args, void *);
	    base = 16;
	    neg = 2;
	    break;
#endif /* unused (and wrong on LLP64 systems) */
    case 's':
      str = va_arg(args, char *);
      break;
    case 'c':
      num[0] = va_arg(args, int);
      num[1] = 0;
      str = num;
      break;
#if 0  /* do we always have strerror() in embedded ? */
	case 'm':
	    str = strerror(errno);
	    break;
#endif /* do we always have strerror() in embedded ? */
    case 'I':
      ip = va_arg(args, u32_t);
      ip = lwip_ntohl(ip);
      ppp_slprintf(num, sizeof(num), "%d.%d.%d.%d", (ip >> 24) & 0xff,
                   (ip >> 16) & 0xff, (ip >> 8) & 0xff, ip & 0xff);
      str = num;
      break;
#if 0         /* need port */
	case 't':
	    time(&t);
	    str = ctime(&t);
	    str += 4;		/* chop off the day name */
	    str[15] = 0;	/* chop off year and newline */
	    break;
#endif        /* need port */
    case 'v': /* "visible" string */
    case 'q': /* quoted string */
      quoted = c == 'q';
      p = va_arg(args, unsigned char *);
      if (p == NULL)
        p = (const unsigned char *)"<NULL>";
      if (fillch == '0' && prec >= 0) {
        n = prec;
      } else {
        n = strlen((const char *)p);
        if (prec >= 0 && n > prec)
          n = prec;
      }
      while (n > 0 && buflen > 0) {
        c = *p++;
        --n;
        if (!quoted && c >= 0x80) {
          OUTCHAR('M');
          OUTCHAR('-');
          c -= 0x80;
        }
        if (quoted && (c == '"' || c == '\\'))
          OUTCHAR('\\');
        if (c < 0x20 || (0x7f <= c && c < 0xa0)) {
          if (quoted) {
            OUTCHAR('\\');
            switch (c) {
            case '\t':
              OUTCHAR('t');
              break;
            case '\n':
              OUTCHAR('n');
              break;
            case '\b':
              OUTCHAR('b');
              break;
            case '\f':
              OUTCHAR('f');
              break;
            default:
              OUTCHAR('x');
              OUTCHAR(hexchars[c >> 4]);
              OUTCHAR(hexchars[c & 0xf]);
            }
          } else {
            if (c == '\t')
              OUTCHAR(c);
            else {
              OUTCHAR('^');
              OUTCHAR(c ^ 0x40);
            }
          }
        } else
          OUTCHAR(c);
      }
      continue;
#if PRINTPKT_SUPPORT
    case 'P': /* print PPP packet */
      bufinfo.ptr = buf;
      bufinfo.len = buflen + 1;
      p = va_arg(args, unsigned char *);
      n = va_arg(args, int);
      ppp_format_packet(p, n, ppp_vslp_printer, &bufinfo);
      buf = bufinfo.ptr;
      buflen = bufinfo.len - 1;
      continue;
#endif /* PRINTPKT_SUPPORT */
    case 'B':
      p = va_arg(args, unsigned char *);
      for (n = prec; n > 0; --n) {
        c = *p++;
        if (fillch == ' ')
          OUTCHAR(' ');
        OUTCHAR(hexchars[(c >> 4) & 0xf]);
        OUTCHAR(hexchars[c & 0xf]);
      }
      continue;
    default:
      *buf++ = '%';
      if (c != '%')
        --fmt; /* so %z outputs %z etc. */
      --buflen;
      continue;
    }
    if (base != 0) {
      str = num + sizeof(num);
      *--str = 0;
      while (str > num + neg) {
        *--str = hexchars[val % base];
        val = val / base;
        if (--prec <= 0 && val == 0)
          break;
      }
      switch (neg) {
      case 1:
        *--str = '-';
        break;
      case 2:
        *--str = 'x';
        *--str = '0';
        break;
      default:
        break;
      }
      len = num + sizeof(num) - 1 - str;
    } else {
      len = strlen(str);
      if (prec >= 0 && len > prec)
        len = prec;
    }
    if (width > 0) {
      if (width > buflen)
        width = buflen;
      if ((n = width - len) > 0) {
        buflen -= n;
        for (; n > 0; --n)
          *buf++ = fillch;
      }
    }
    if (len > buflen)
      len = buflen;
    memcpy(buf, str, len);
    buf += len;
    buflen -= len;
  }
  *buf = 0;
  return buf - buf0;
}

#if PRINTPKT_SUPPORT
/*
 * vslp_printer - used in processing a %P format
 */
static void ppp_vslp_printer(void *arg, const char *fmt, ...) {
  int n;
  va_list pvar;
  struct buffer_info *bi;

  va_start(pvar, fmt);
  bi = (struct buffer_info *)arg;
  n = ppp_vslprintf(bi->ptr, bi->len, fmt, pvar);
  va_end(pvar);

  bi->ptr += n;
  bi->len -= n;
}
#endif /* PRINTPKT_SUPPORT */

#if 0  /* UNUSED */
/*
 * log_packet - format a packet and log it.
 */

void
log_packet(p, len, prefix, level)
    u_char *p;
    int len;
    char *prefix;
    int level;
{
	init_pr_log(prefix, level);
	ppp_format_packet(p, len, pr_log, &level);
	end_pr_log();
}
#endif /* UNUSED */

#if PRINTPKT_SUPPORT
/*
 * ppp_format_packet - make a readable representation of a packet,
 * calling `printer(arg, format, ...)' to output it.
 */
static void ppp_format_packet(const u_char *p, int len,
                              void (*printer)(void *, const char *, ...),
                              void *arg) {
  int i, n;
  u_short proto;
  const struct protent *protp;

  if (len >= 2) {
    GETSHORT(proto, p);
    len -= 2;
    for (i = 0; (protp = protocols[i]) != NULL; ++i)
      if (proto == protp->protocol)
        break;
    if (protp != NULL) {
      printer(arg, "[%s", protp->name);
      n = (*protp->printpkt)(p, len, printer, arg);
      printer(arg, "]");
      p += n;
      len -= n;
    } else {
      for (i = 0; (protp = protocols[i]) != NULL; ++i)
        if (proto == (protp->protocol & ~0x8000))
          break;
      if (protp != 0 && protp->data_name != 0) {
        printer(arg, "[%s data]", protp->data_name);
        if (len > 8)
          printer(arg, "%.8B ...", p);
        else
          printer(arg, "%.*B", len, p);
        len = 0;
      } else
        printer(arg, "[proto=0x%x]", proto);
    }
  }

  if (len > 32)
    printer(arg, "%.32B ...", p);
  else
    printer(arg, "%.*B", len, p);
}
#endif /* PRINTPKT_SUPPORT */

#if 0  /* UNUSED */
/*
 * init_pr_log, end_pr_log - initialize and finish use of pr_log.
 */

static char line[256];		/* line to be logged accumulated here */
static char *linep;		/* current pointer within line */
static int llevel;		/* level for logging */

void
init_pr_log(prefix, level)
     const char *prefix;
     int level;
{
	linep = line;
	if (prefix != NULL) {
		ppp_strlcpy(line, prefix, sizeof(line));
		linep = line + strlen(line);
	}
	llevel = level;
}

void
end_pr_log()
{
	if (linep != line) {
		*linep = 0;
		ppp_log_write(llevel, line);
	}
}

/*
 * pr_log - printer routine for outputting to log
 */
void
pr_log (void *arg, const char *fmt, ...)
{
	int l, n;
	va_list pvar;
	char *p, *eol;
	char buf[256];

	va_start(pvar, fmt);
	n = ppp_vslprintf(buf, sizeof(buf), fmt, pvar);
	va_end(pvar);

	p = buf;
	eol = strchr(buf, '\n');
	if (linep != line) {
		l = (eol == NULL)? n: eol - buf;
		if (linep + l < line + sizeof(line)) {
			if (l > 0) {
				memcpy(linep, buf, l);
				linep += l;
			}
			if (eol == NULL)
				return;
			p = eol + 1;
			eol = strchr(p, '\n');
		}
		*linep = 0;
		ppp_log_write(llevel, line);
		linep = line;
	}

	while (eol != NULL) {
		*eol = 0;
		ppp_log_write(llevel, p);
		p = eol + 1;
		eol = strchr(p, '\n');
	}

	/* assumes sizeof(buf) <= sizeof(line) */
	l = buf + n - p;
	if (l > 0) {
		memcpy(line, p, n);
		linep = line + l;
	}
}
#endif /* UNUSED */

/*
 * ppp_print_string - print a readable representation of a string using
 * printer.
 */
void ppp_print_string(const u_char *p, int len,
                      void (*printer)(void *, const char *, ...), void *arg) {
  int c;

  printer(arg, "\"");
  for (; len > 0; --len) {
    c = *p++;
    if (' ' <= c && c <= '~') {
      if (c == '\\' || c == '"')
        printer(arg, "\\");
      printer(arg, "%c", c);
    } else {
      switch (c) {
      case '\n':
        printer(arg, "\\n");
        break;
      case '\r':
        printer(arg, "\\r");
        break;
      case '\t':
        printer(arg, "\\t");
        break;
      default:
        printer(arg, "\\%.3o", (u8_t)c);
        /* no break */
      }
    }
  }
  printer(arg, "\"");
}

/*
 * ppp_logit - does the hard work for fatal et al.
 */
static void ppp_logit(int level, const char *fmt, va_list args) {
  char buf[1024];

  ppp_vslprintf(buf, sizeof(buf), fmt, args);
  ppp_log_write(level, buf);
}

static void ppp_log_write(int level, char *buf) {
  LWIP_UNUSED_ARG(
      level); /* necessary if PPPDEBUG is defined to an empty function */
  LWIP_UNUSED_ARG(buf);
  PPPDEBUG(level, ("%s\n", buf));
#if 0
    if (log_to_fd >= 0 && (level != LOG_DEBUG || debug)) {
	int n = strlen(buf);

	if (n > 0 && buf[n-1] == '\n')
	    --n;
	if (write(log_to_fd, buf, n) != n
	    || write(log_to_fd, "\n", 1) != 1)
	    log_to_fd = -1;
    }
#endif
}

/*
 * ppp_fatal - log an error message and die horribly.
 */
void ppp_fatal_impl(const char *fmt, ...) {
  va_list pvar;

  va_start(pvar, fmt);
  ppp_logit(LOG_ERR, fmt, pvar);
  va_end(pvar);

  LWIP_ASSERT("ppp_fatal", 0); /* as promised */
}

/*
 * ppp_error - log an error message.
 */
void ppp_error_impl(const char *fmt, ...) {
  va_list pvar;

  va_start(pvar, fmt);
  ppp_logit(LOG_ERR, fmt, pvar);
  va_end(pvar);
#if 0  /* UNUSED */
    ++error_count;
#endif /* UNUSED */
}

/*
 * ppp_warn - log a warning message.
 */
void ppp_warn_impl(const char *fmt, ...) {
  va_list pvar;

  va_start(pvar, fmt);
  ppp_logit(LOG_WARNING, fmt, pvar);
  va_end(pvar);
}

/*
 * ppp_notice - log a notice-level message.
 */
void ppp_notice_impl(const char *fmt, ...) {
  va_list pvar;

  va_start(pvar, fmt);
  ppp_logit(LOG_NOTICE, fmt, pvar);
  va_end(pvar);
}

/*
 * ppp_info - log an informational message.
 */
void ppp_info_impl(const char *fmt, ...) {
  va_list pvar;

  va_start(pvar, fmt);
  ppp_logit(LOG_INFO, fmt, pvar);
  va_end(pvar);
}

/*
 * ppp_dbglog - log a debug message.
 */
void ppp_dbglog_impl(const char *fmt, ...) {
  va_list pvar;

  va_start(pvar, fmt);
  ppp_logit(LOG_DEBUG, fmt, pvar);
  va_end(pvar);
}

#if PRINTPKT_SUPPORT
/*
 * ppp_dump_packet - print out a packet in readable form if it is interesting.
 * Assumes len >= PPP_HDRLEN.
 */
void ppp_dump_packet(ppp_pcb *pcb, const char *tag, unsigned char *p, int len) {
  int proto;

  /*
   * don't print data packets, i.e. IPv4, IPv6, VJ, and compressed packets.
   */
  proto = (p[0] << 8) + p[1];
  if (proto < 0xC000 && (proto & ~0x8000) == proto)
    return;

  /*
   * don't print valid LCP echo request/reply packets if the link is up.
   */
  if (proto == PPP_LCP && pcb->phase == PPP_PHASE_RUNNING &&
      len >= 2 + HEADERLEN) {
    unsigned char *lcp = p + 2;
    int l = (lcp[2] << 8) + lcp[3];

    if ((lcp[0] == ECHOREQ || lcp[0] == ECHOREP) && l >= HEADERLEN &&
        l <= len - 2)
      return;
  }

  ppp_dbglog(("%s %P", tag, p, len));
}
#endif /* PRINTPKT_SUPPORT */

#if 0 /* Unused */

/*
 * complete_read - read a full `count' bytes from fd,
 * unless end-of-file or an error other than EINTR is encountered.
 */
ssize_t
complete_read(int fd, void *buf, size_t count)
{
	size_t done;
	ssize_t nb;
	char *ptr = buf;

	for (done = 0; done < count; ) {
		nb = read(fd, ptr, count - done);
		if (nb < 0) {
			if (errno == EINTR)
				continue;
			return -1;
		}
		if (nb == 0)
			break;
		done += nb;
		ptr += nb;
	}
	return done;
}

/* Procedures for locking the serial device using a lock file. */
#ifndef LOCK_DIR
#ifdef __linux__
#define LOCK_DIR "/var/lock"
#else
#ifdef SVR4
#define LOCK_DIR "/var/spool/locks"
#else
#define LOCK_DIR "/var/spool/lock"
#endif
#endif
#endif /* LOCK_DIR */

static char lock_file[MAXPATHLEN];

/*
 * lock - create a lock file for the named device
 */
int
lock(dev)
    char *dev;
{
#ifdef LOCKLIB
    int result;

    result = mklock (dev, (void *) 0);
    if (result == 0) {
	ppp_strlcpy(lock_file, dev, sizeof(lock_file));
	return 0;
    }

    if (result > 0)
        ppp_notice(("Device %s is locked by pid %d", dev, result));
    else
	ppp_error(("Can't create lock file %s", lock_file));
    return -1;

#else /* LOCKLIB */

    char lock_buffer[12];
    int fd, pid, n;

#ifdef SVR4
    struct stat sbuf;

    if (stat(dev, &sbuf) < 0) {
	ppp_error(("Can't get device number for %s: %m", dev));
	return -1;
    }
    if ((sbuf.st_mode & S_IFMT) != S_IFCHR) {
	ppp_error(("Can't lock %s: not a character device", dev));
	return -1;
    }
    ppp_slprintf(lock_file, sizeof(lock_file), "%s/LK.%03d.%03d.%03d",
	     LOCK_DIR, major(sbuf.st_dev),
	     major(sbuf.st_rdev), minor(sbuf.st_rdev));
#else
    char *p;
    char lockdev[MAXPATHLEN];

    if ((p = strstr(dev, "dev/")) != NULL) {
	dev = p + 4;
	strncpy(lockdev, dev, MAXPATHLEN-1);
	lockdev[MAXPATHLEN-1] = 0;
	while ((p = strrchr(lockdev, '/')) != NULL) {
	    *p = '_';
	}
	dev = lockdev;
    } else
	if ((p = strrchr(dev, '/')) != NULL)
	    dev = p + 1;

    ppp_slprintf(lock_file, sizeof(lock_file), "%s/LCK..%s", LOCK_DIR, dev);
#endif

    while ((fd = open(lock_file, O_EXCL | O_CREAT | O_RDWR, 0644)) < 0) {
	if (errno != EEXIST) {
	    ppp_error(("Can't create lock file %s: %m", lock_file));
	    break;
	}

	/* Read the lock file to find out who has the device locked. */
	fd = open(lock_file, O_RDONLY, 0);
	if (fd < 0) {
	    if (errno == ENOENT) /* This is just a timing problem. */
		continue;
	    ppp_error(("Can't open existing lock file %s: %m", lock_file));
	    break;
	}
#ifndef LOCK_BINARY
	n = read(fd, lock_buffer, 11);
#else
	n = read(fd, &pid, sizeof(pid));
#endif /* LOCK_BINARY */
	close(fd);
	fd = -1;
	if (n <= 0) {
	    ppp_error(("Can't read pid from lock file %s", lock_file));
	    break;
	}

	/* See if the process still exists. */
#ifndef LOCK_BINARY
	lock_buffer[n] = 0;
	pid = atoi(lock_buffer);
#endif /* LOCK_BINARY */
	if (pid == getpid())
	    return 1;		/* somebody else locked it for us */
	if (pid == 0
	    || (kill(pid, 0) == -1 && errno == ESRCH)) {
	    if (unlink (lock_file) == 0) {
		ppp_notice(("Removed stale lock on %s (pid %d)", dev, pid));
		continue;
	    }
	    ppp_warn(("Couldn't remove stale lock on %s", dev));
	} else
	    ppp_notice(("Device %s is locked by pid %d", dev, pid));
	break;
    }

    if (fd < 0) {
	lock_file[0] = 0;
	return -1;
    }

    pid = getpid();
#ifndef LOCK_BINARY
    ppp_slprintf(lock_buffer, sizeof(lock_buffer), "%10d\n", pid);
    write (fd, lock_buffer, 11);
#else
    write(fd, &pid, sizeof (pid));
#endif
    close(fd);
    return 0;

#endif
}

/*
 * relock - called to update our lockfile when we are about to detach,
 * thus changing our pid (we fork, the child carries on, and the parent dies).
 * Note that this is called by the parent, with pid equal to the pid
 * of the child.  This avoids a potential race which would exist if
 * we had the child rewrite the lockfile (the parent might die first,
 * and another process could think the lock was stale if it checked
 * between when the parent died and the child rewrote the lockfile).
 */
int
relock(pid)
    int pid;
{
#ifdef LOCKLIB
    /* XXX is there a way to do this? */
    return -1;
#else /* LOCKLIB */

    int fd;
    char lock_buffer[12];

    if (lock_file[0] == 0)
	return -1;
    fd = open(lock_file, O_WRONLY, 0);
    if (fd < 0) {
	ppp_error(("Couldn't reopen lock file %s: %m", lock_file));
	lock_file[0] = 0;
	return -1;
    }

#ifndef LOCK_BINARY
    ppp_slprintf(lock_buffer, sizeof(lock_buffer), "%10d\n", pid);
    write (fd, lock_buffer, 11);
#else
    write(fd, &pid, sizeof(pid));
#endif /* LOCK_BINARY */
    close(fd);
    return 0;

#endif /* LOCKLIB */
}

/*
 * unlock - remove our lockfile
 */
void
unlock()
{
    if (lock_file[0]) {
#ifdef LOCKLIB
	(void) rmlock(lock_file, (void *) 0);
#else
	unlink(lock_file);
#endif
	lock_file[0] = 0;
    }
}

#endif /* Unused */

#endif /* PPP_SUPPORT */
